重点知识
一、 加载collectionView注意事项
1.创建collectionView,有两种方式 ：一种是xib和一种是纯代码；设置代理和数据源，注册cell,配置流水布局的属性，如上、下、左、右间距及行间距和列间距。
2. 创建CollectionViewCell，实现collectionView代理和数据源方法。
3. 设置每个cell的尺寸。
4.cell出现时显示动画
二、 流水布局思路分析
三、精华代码
1、布局一
//1.配置collectionView
self.automaticallyAdjustsScrollViewInsets = YES; //默认为No,
[self.view setBackgroundColor:[UIColor yellowColor]];
[self.collectionView registerNib:[UINib nibWithNibName:@"STRNearPeopleCell" bundle:nil] forCellWithReuseIdentifier:nearPeopleCell];
NSLog(@"%@",self.dataList);
[self.collectionView reloadData];
//2.显示动画及设置大小 和加载cell - (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath{
STRNearPeopleCell *hotcell = (STRNearPeopleCell *)cell;
[hotcell showAnamil]; }
//流水布局，系统UICollectionViewLayout.h
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{
CGFloat outInset = self.collectionView.frame.size.width - 2 * kMargin;
NSInteger count = outInset / kItemSizeW;
NSInteger extraTotal = (NSInteger)(outInset - kMargin * (count - 1 )); CGFloat itemWH; if (extraTotal < count * kItemSizeW) { itemWH = extraTotal / count;
} else {
CGFloat extraWidth = extraTotal % kItemSizeW;
itemWH = kItemSizeW + extraWidth / count;
}
return CGSizeMake(itemWH, itemWH + 25);
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
return self.dataList.count;
} // The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath:
- (__kindof UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{ STRNearPeopleCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:nearPeopleCell forIndexPath:indexPath];
return cell;
} //3.设置cell
- (void)awakeFromNib {
[super awakeFromNib];
// Initialization code
}
//此外是模拟数据，真实的话把注释取消掉，用来控制显示动画的。
- (void)showAnamil {
//x和y的最终值为1
// if (self.live.isShow) { //当有网络模型时，可以把isShow字段加进去
// return;
// }
self.layer.transform = CATransform3DMakeScale(0.1, 0.1, 1); [UIView animateWithDuration:1 animations:^{
self.layer.transform = CATransform3DMakeScale(1, 1, 1);
// self.live.show = YES; //如果已经显示过yes
}];
}
2、布局二
//定义每个UICollectionView 的大小
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
return CGSizeMake(([UIScreen mainScreen].bounds.size.width-64) /3 ,([UIScreen mainScreen].bounds.size.width-64) /3);
} //定义每个UICollectionView 的 margin
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
return UIEdgeInsetsMake(20, 8, 20, 8);
}